The present invention relates generally to a diffractive optical system, and more particularly to a diffractive optical system that can be used as an optical device such as a phase shift mask for fabrication of optical elements having a fine periodic structure, and a light beam splitter.
As well known typically from patent publication 1, a phase type diffraction grating is used as a light beam splitter. As also known typically from patent publication 2, exposure of a fine structure using a phase shift mask having a phase structure is practiced in the form of an phase shift mask.
Patent Publication 1
JP(A)7-140311
Patent Publication 2
JP(A)5-134389
Non-Patent Publication 1
“Optics”, Vol. 32, No. 8 (2003), pp. 489–491